Building touring bike for daughter

One of my daughters (4'9") wants a touring bike so that she can join my on my rides.
My brother-in-law took her to a bicycle store in Portland. OR for some test riding when she was visiting family last month. They determined the best frame size for her was 40cm. Apparently the closest to this without the expense of a custom build is the 42cm Surly LHT.  She tried one of these and thought it would work out frame size wise, but had a hard time putting her small hands around the brake levers. I've decided to buy the frame then build the bike to fit her the best I can. If anyone on the list has experience with fitting touring bikes to smaller riders, I'd appreciate any input.

Thanks,
kw.